None
Not Applicable
1. Field of the Invention
This invention relates generally to tension cable actuators for ergonomic devices such as lumbar supports.
2. Related Art
Ergonomic supports for seats, especially lumbar supports for automobile seats, are frequently moved into supporting positions from flat positions by means of tension cables, such as Bowden cables. Bowden cables are simple, coaxial mechanical devices wherein a wire slides axially through a sleeve or conduit. Manufactures of moveable devices that support the weight of a seat passenger, especially devices designed to operate in dynamic tension, find that Bowden cables are an efficient way to apply traction to the moving parts of the ergonomic device. A Bowden cable sleeve end is anchored to one part of the ergonomic device, and the Bowden cable wire end to another part of the moving device. The two elements can be anchored to different portions of a single moving part, as in the case of an arching pressure surface that slides along guide rails. Alternatively, either the sleeve end or the wire end can be anchored to a non-moving portion, such as the housing of a push paddle type support, while the other element is anchored to the moving part of the device, such as the extending push paddle itself. When anchored, drawing the Bowden cable wire through the Bowden cable sleeve causes the moving parts of an ergonomic support device to travel from a relaxed, non-supporting or flat position to a tensioned, supporting position such as a bowed arch or an extended paddle.
Traction is applied to draw the wire of a Bowden cable through the sleeve of a Bowden cable by a variety of means which act on the end of the Bowden cable opposite the ergonomic device. For more expensive models of lumbar support, an electric motor is used. For devices to be installed in more economical seats, mechanical actuators are used. Typical prior art mechanical actuators anchored the Bowden cable sleeve to a stationary housing and anchored the Bowden cable wire to a moving nut threading into the housing. Turning the nut so that the threads extended it out of the housing had the effect of drawing the Bowden cable wire axially out of the Bowden cable sleeve at the actuator end. This action was translated to the ergonomic device end of the Bowden cable in order to put tension on the moving parts of the ergonomic device and bring it into a tensioned, supporting position. A typical lumbar support for a typical automobile seat travels from flat to an arched or extended position that is displaced as much as 50 mm from the flat position. Prior art manual screw type actuators required a passenger to make anywhere from four to seven complete turns of the screw nut in order to take the lumbar support through its entire range of travel.
Highly competitive markets for automobile seats and furniture place a premium on optimization of comfort and convenience for a seat occupant. There is need in the industry for a manual actuator that extends an ergonomic support device through its range of travel with fewer turns of the actuator nut by the passenger. There is also a continuing need in the industry for reducing the complication of assemblies, reducing packaging size, reducing cost, and increasing durability.
The present invention is a manual, screw type tension cable actuator that moves the connected ergonomic device through its full range of travel using half as many turns as required by prior art actuators. By requiring fewer turns, the device is more convenient for the seat passenger.
The task of the actuator is achieved by sliding the end of the Bowden cable wire axially out of the end of the Bowden cable sleeve. Accordingly, any device that moves the wire end and the sleeve end apart from one another applies the tension necessary to actuate the ergonomic device at other end of the Bowden cable. Prior art mechanical screw type actuators held the Bowden cable sleeve end stationary while drawing the Bowden cable wire end axially out of the sleeve. The present invention draws the Bowden cable wire across a pulley that is attached to a lead screw. The pulley causes twice the length of wire to be drawn out of the Bowden cable sleeve as the length that the screw is translated when the nut is turned.
In the present invention a housing holds a rotating nut, and allows it to be mounted on a seat frame. Threads inside the nut engage corresponding threads on the outside of a lead screw. At the inner end of the lead screw, preferably within the housing, is a cradle for a pulley. The cradle and the pulley it holds move axially through the housing as the screw is turned by the nut. A Bowden cable is achored to the housing at the pulley end. The Bowden cable sleeve is anchored in a seat at the end of the housing. The wire extending out of the Bowden cable is threaded through the housing, around the pulley, and back in the direction of the sleeve seat, where a second seat in the housing anchors the end of the Bowden cable wire. A passenger turns the nut which translates the lead screw outward from the housing, moving the pulley outward with it. The pulley pulls the Bowden cable wire out from the Bowden cable sleeve. The wire must be pulled out of the sleeve twice as far as the lead screw travels. Thus, a single turn of the nut achieves twice the separation travel between the wire end and the sleeve end as was achieved by the prior art, simple screw manual actuator. Accordingly, the ergonomic device may be run through its range of travel with half as many turns of the nut by a passenger.
Further features and advantages of the present invention, as well as the structure and operation of various embodiments of the present invention, are described in detail below, with reference to the accompanying drawings.